Comparative studies of several methods to determine the dynamic fracture toughness of a nuclear pressure vessel steel A508 CL3 with Charpy-size specimen
✍ Scribed by Zhang Xinping; Shi Yaowu
- Publisher
- Springer Netherlands
- Year
- 1996
- Tongue
- English
- Weight
- 602 KB
- Volume
- 81
- Category
- Article
- ISSN
- 1573-2673
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✦ Synopsis
In this investigation, five estimation methods have been adopted to estimate the dynamic fracture toughness of a nuclear pressure vessel steel A508 CL3 by using pre-cracked Charpy-size specimens on an instrumented impact test machine. Furthermore, the merits and the demerits of the five methods have also been compared. The experimental results indicate that the maximum load energy method based on the curve of load versus load-point displacement overestimates the dynamic fracture toughness Jta, especially above room temperature. The method of compliance changing rate underestimates the dynamic fracture toughness. The method of measuring the critical stretch zone width (SZWc) at the crack tip by means of SEM fractography and then converting the SZWc into J1~ has a relatively large error. In addition, it is expensive and difficult to measure the SZWc. The method of energy revised at the maximum load may be considered a better single-specimen method for determining the dynamic fracture toughness. Furthermore, the results indicate that although the dynamic resistance curve method can exactly estimate the dynamic fracture toughness of the material, this method needs several specimens. Moreover, the test procedure is complicated. Thus, it is not suitable for nuclear reactor pressure vessel embrittlement surveillance.